In June, a report by the East Bay Municipal Utility District, which provides drinking water to 1.4 million people, announced that a cancer-causing compound in the East Bay water supply had reached a near critical level, “with concentrations of the compound higher than they have been in the last 20 years.” 1

The compound at issue is trihalomethanes or THMs. THMs, known to cause cancer in laboratory animals, form when chlorine, used to disinfect, reacts with organic matter in the water.2 Although it’s always in the water, concentrations of THMs have increased sharply in the last few years with the drought being partly to blame.

The EPA allowable amount is 80 parts per billion but East Bay MUD’s goal is much more strict at 40 parts per billion.


East Bay MUD spokeswoman Andrea Pook said:

“So when people are using less water, it means the water sits longer in our system, which means we need to add additional chlorine to make sure that it does not dissipate.” 3

East Bay MUD will explore other ways to treat the water, perhaps adding new chemicals and changing equipment at treatment plants, and thereby lowering the levels of cancer-causing elements in the water.



Sources and References

  1. KRON 4, June 13, 2017.
  2. KRON 4, June 13, 2017.
  3. KRON 4, June 13, 2017.